In considering means for improving the thermal efficiency of overall laser operation, one important consideration is the thermal conductivity of insulation materials surrounding the laser discharge chamber. A common approach is to use a single material of a predetermined thermal conductivity as insulation. However, one of the problems which arises in using only one type of insulation material is that its thermal conductivity may be insufficient, within certain temperature ranges, to provide optimum temperature parameters required for overall efficient laser operation. As an example, in a metal vapor laser such as a copper vapor laser, insulation material is usually utilized which provides the least thermal conductivity in the temperature range of about 1600.degree. C. (the approximate interior temperature of the copper vapor laser) to about room temperature, which is the temperature of the environment of the laser. However, a single insulation material generally is not capable of providing suitable thermal conductivity within such a temperature range for maximum efficiency of operation of the laser.